In recent years, electronic devices with image acquisition functions have become popular with consumers. Typically, a camera module employed in an electronic device, e.g., a personal computer or a cell phone, includes an image sensor that captures incident light to form an electronic representation of an image. That is, the image sensor is a semiconductor device that converts optical image signals into electrical image signals. The electronic device may not configure the image sensors properly as various types of image sensors need different settings. Moreover, the camera module usually includes an electrically erasable programmable read-only memory (E2PROM) to store configuration data of the image sensor. However, cost of the camera module can be increased by the adoption of the E2PROM.